Abstract: Modulation Transfer Function of an electro-optical sensor is measured by focusing a square or rectangular target image onto the sensor and deriving the Modulation Transfer Function in two directions simultaneously from an output of the sensor. The target image is tilted with respect to the sensor's focal plane array such that the target image's edges cross different detector elements at different phases. The target image can be rotated over finely spaced intervals. Modulation Transfer Function can be derived using a least squares method or using a one-dimensional Fourier Transform in both horizontal and vertical directions.